Work towards a fully operational planar system continued during this period. The elements of the system include a gamma camera, an imaging bed, custom-designed and commercially available Nuclear Instrumentation Modules (NIMs), and a data acquisition and timing board within a Macintosh II computer. Correction circuitry for improving spatial linearity, count rate, and energy sensitivity have been completed. Design requirements for this device included production of high-spatial-resolution planar images at low gamma-ray energies (100-150 kev) over a field of view commensurate with small animal sizes (5 x 5 cm, nominal), and simplicity of event positioning within the field of view to minimize electronic complexity.